Wilms' tumor

ABSTRACT

Wilms' Tumor, also know as nephroblastoma, is a childhood renal tumor. The assessment and diagnosis of a Wilms' tumor is one of the many challenges faced in the primary care setting. This article presents a brief review of Wilms' tumor in the pedi atric population and its occurrence in a case presentation.

Incidence

Wilms' tumor accounts for 7% of all solid tumors in children.1 Occurring in 1 of every 15,000 live births per year in the United States, it is the most common childhood renal malignancy.1 Approximately 500 new cases present annually in the United States,2 and the number of cases in other countries appears to be equal. Wilms' tumor occurs equally in boys and girls, more commonly in the left kidney, and bilaterally in 4% to 9% of the cases.1 It is slightly more common in black children.3 Peak age for presentation is between ages 2 and 3,4 but most children present between ages 1 and 5.[3] Children rarely present past age 7.

Etiology

The tumor arises from undifferentiated primordial cells.1 The tumor consists of three principle components: undifferentiated blasternal cells, epithelial tissue, and tumor connective tissue.2 Different theories exist, but general belief is that Wilms' tumors arise during intrauterine life from undifferentiated embryonic tissues.

Different congenital anomalies have been associated with Wilms' tumor: aniridia, hemihypertrophy, and malformations of the genitalia such as cryptorchidism, hypospadias, pseudohermaphroditism, and gonadal dysgenesis.5 An increased incidence of Wilms' tumor has been seen in patients with Beckwith-Wiedmann syndrome and neurofibromatosis.4

Clinical Manifestations

Wilms' tumor usually presents in the form of a large abdominal mass. The parent or guardian usually first discovers the abdominal mass during bathing or dressing, although the child appears healthy. Other presenting signs and symptoms include vague abdominal pain, hematuria, fever, weight loss, hypertension, and anorexia.2

Evaluation

Different laboratory tests and imaging procedures are used to assist in the diagnosis of Wilms' tumor. Laboratory tests include a complete blood count, electrolyte levels, a urinalysis, and liver and kidney function tests. Imaging procedures include an ultrasound and a computed tomography (CT) scan of the abdomen. A chest X-ray, a CT scan of the head, and a bone scan may be used to detect other tumors or the presence of metastatic disease.

Differential Diagnosis

Differential diagnoses include polycystic kidney, renal hematoma, renal abscess, neuroblastoma, and other neoplasms of the kidney such as clear cell carcinoma and rhabdoid tumor.4

Diagnosis, Referral, and Treatment

Once the diagnosis of Wilms' Tumor is suspected, an immediate referral to a pediatric oncologist is made for acute care. The diagnosis of Wilms' tumor is confirmed in the operating room. The abdomen is explored, a nephrectomy is performed, and the tumor is sent to pathology.

A staging system developed by the Third National Wilms' Tumor Study assists in determining prognosis and treatment for children with this tumor (see Table 1). Prognosis is affected by factors such as metastases and disease stage, but the most important factors are the histologic category and regional lymph node involvement (see Table 2).

Wilms' tumor treatment consists of surgery, radiation, and chemotherapy.6 Treatment is based on the stage and histology of the disease. Radiation is used in stages III and IV and when metastases are present Radiation is most effective if it is begun 1 to 3 days postoperatively.3 The chemotherapy protocol is currently under study for each stage.3 The combination of chemotherapy drugs, vincristine and actinomycin D, has been shown to be most effective.3 Survival rates for stage III have increased with the addition of doxorubicin hydrochloride to the current protocol of vincristine and actinomycin D.3

Case Presentation

B.J., a 3-year-old African-American boy, presented to a primary care practitioner's office with a 2-day onset of a "swollen abdomen." B.J. and his grandfather denied constipation, pain, discomfort, fever, and hematuria. B.J. had not experienced any changes in his activity level or dietary intake. His medical history was unremarkable except for having the sickle cell trait. Family history was unremarkable. He had no drug or food allergies, and his immunizations were current.

Physical examination revealed an alert boy in no apparent distress, with no signs of a toxic reaction. BJ. was normocephalic with tympanic membranes that were mobile and had visible landmarks. His pupils were 3/3 equal and reactive to light. The oropharynx was normal. His neck was supple without significant adenopathy. Bilateral breath sounds were equal and clear to auscultation.

His heart had a regular rate and rhythm without murmurs, gallops, and thrills. His abdomen had a 10-- cm firm mass in the left upper quadrant with detectable margins. No other abnormalities were detected. He was circumcised with bilaterally descended testes. His neurologic examination was normal, and his skin was without rash or lesions.

A flat-plate X-ray of the abdomen revealed a 10-cm mass in the left upper quadrant. No calcification was seen. An ultrasound of the mass revealed it to be consistent with a Wilms' tumor.

B.J. was immediately referred to a pediatric oncologist at the nearest tertiary pediatric center for evaluation and definitive treatment. He underwent a left nephrectomy and removal of the Wilms' tumor. The pathology report revealed a tumor in stage I with unfavorable histology. B.J. is currently undergoing chemotherapy according to the institution's Wilms' tumor treatment protocol.

REFERENCES

1. Nemes J, Donahue MC: Solid tumors in children. In: Nursing Clinics Of North America. Philadelphia, Pa.: XB. Saunders Co., 1994;29(4):585-98.

2. Stanfill P, Green A: Wilms' tumor. In: Hockenberry MJ, Coody DK, eds. Pediatric Oncology and Hematology: Perspectives On Care. St. Louis,

Mo.: The C.V Mosby Company, 1986:81-91.

3. McCance KL, Huether SE. Pathophysiology: The Biologic Basis for Disease in Adults and Children, 2nd edition. St. Louis, Mo.: Mosby, 1994:1274-75.

4. Schwartz MW; ed. The 5 Minute Pediatric Consult. Baltimore, Md.: Williams & Wilkins, 1997: 816-17.

5. D'Angio G, Beckw ith J, Breslow N, et al.: Wilms' tumor. In: Pizzo, PA, Poplack DG, eds. Principles and Practice of Pediatric Oncology, Philadelphia, Pa.: J.B. Lippincott Co., 1989:583-606.

6. Sharpe CR, Franco EL: Etiology of Wilms' tumor. Epidemiologic Reviews 1995;17(2):415-32.

ACKNOWLEDGMENT

The author wishes to thank Ralph Vogel, RN, PNP, from the College of Nursing at the University of Arkansas for Medical Sciences for his guidance and review of this manuscript.

Cheryl Cummings Stegbauer, CFNC, PhD, editor of this column, is an Associate Professor at the University of Tennessee, Memphis.

ABOUT THE AUTHOR

Sherry Pye, RNP, PNP, CCRN, MNSc, is a pediatric nurse practitioner in the Arkansas Children's Hospital's Cardiovascular Intensive Care Unit, Little Rock, Ark.

Copyright Springhouse Corporation May 1999
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